SU1703025A1 - Method of dairy produce pasteurization into the capacity - Google Patents

Abstract

The invention relates to the food industry and can be used in the pasteurization of dairy products, in particular in the manufacture of rennet cheese in factories and in shops for the processing of milk of relatively low power. The purpose of the invention is to reduce processing time and improve product quality. The method includes heating with simultaneous mixing to the pasteurization temperature, holding and conducting cooling to a predetermined temperature. Heating is carried out by bubbling saturated water vapor in the bottom layer, after holding the vessel is sealed and then evacuated to the initial temperature of the dairy product, and the diameter of the vapor bubble is chosen from the ratio d 1.82 g ft x. x (r + c0) 4gded 9.8m: / s2; / 3-volume expansion of milk, v, I-kinematic viscosity, m2 / s2, thermal conductivity, respectively. W / m-deg; g, c, respectively, the heat of condensation, J / kg, and the heat capacity of steam, J / kg, deg; © - average temperature gradient in milk, hail; G is the steam supply per unit of the horizontal surface of the container, kg / m2-s; g is the frequency of mixing, s. In order to regulate the moisture content of the dairy product during the vacuuming process, conductive heating or additional cooling is carried out. 1 hp f-ly. 2 Il. (/ С N About so

Description

The invention relates to the food industry and can be used in the pasteurization and cooling of dairy products, in particular in the manufacture of rennet cheeses, such as Poshekhon and Dutch, in cheese factories and in shops for the processing of milk of relatively low power.

The purpose of the invention is to reduce the processing time and increase the quality of the product.

...., /,.: -V--.Vi; .-:. :: -. - .. -.

FIG. 1 shows a schematic diagram of an installation that implements a method for the inspection and cooling of dairy products; in fig. 2 - capacity, longitudinal section ..

The installation comprises a tank 1 with a lid 2 and a jacket 3 for the heat carrier, a stirrer 4, a source 5 of the heat carrier and a source 6 of the carrier fluid (water or ice on water). The unit is equipped with a bubbler 7. placed at the bottom of the tank, with a vacuum pump B, for example, with a hydraulic ring connected to the steam cavity 9 of the tank. The source of heat carrier is made in the form of a steam boiler with a valve 10 and a throttle washer 11 with a dry steam capacity of 100-300 kg / h and an overpressure of 0.7 these. The bubbler is combined with a stirrer and is made in the form of a perforated tube installed across the bottom of the tank with the possibility of longitudinal reciprocating motion. The diameter of the holes or the width of the main corresponds to the initial diameter of the bubbled vapor bubbles. The water inlet of the ring pump is connected to the source of coolant and the outlet to the tank jacket.

The dairy products pasteurization method is carried out as follows.

The container is pre-sterilized and filled with milk. The coolant in the form of saturated water vapor with a pressure of up to 0.7 is fed into the bubbler-mixer, moving it t along the tank, as a result of which the loop from the bubbles is unrolled as a horizontal curtain that slowly rises in the layer of dairy product after one pass of the bubbler -mixers At the same time, vapor bubbles gradually condense and decrease in diameter, transferring the heat of condensation to nearby liquid layers by convection. In order to avoid local overheating of the dairy product, the diameter of the bubbles is chosen from the ratio

tf-.1,82g 0

in G An (r + c0

40

where g is 9.8 m / s2; - - P is the volume expansion of milk,

Grade 1:

. V, I - respectively kinematic

 )} ..

viscosity, m / s, and thermal conductivity, W / mg 45 degrees; .

g, c-according to the heat of condensation, j / kg. and heat capacity of steam, j / kg “hail;

0- average temperature gradient in mr-50, hail;

G - steam supply per unit of the horizontal surface of the tank, kg / m2 С;

n is the frequency of movement,.

After displacing the vapor curtain from the bottom 55 layer of the tank with cold milk, the bubbler-agitator is moved in the opposite direction and the bubbling cycle is repeated. condensation and heating of the layers of milk to a predetermined temperature of 75 ° C, not 0 5

0 5 0 5

0

five

0

five

bypassed in the manufacture of rennet cheese. The frequency of movement of the barbohera mixer, corresponding to the frequency of the steam supply, is chosen based on the time of passage of the steam curtain through the bottom layer of the tank with a thickness corresponding to the diameter of the barber pipe. This time should not exceed the time of the existence (condensation) of vapor bubbles. For typical drives of dairy product mixers, the maximum movement frequency does not exceed 20 hours.

After holding the dairy product at a pasteurization temperature of 75 ° C, a cooling process is carried out. Seal the container with a cap. The vapor-air mixture is pumped out, gradually lowering the pressure in the tank from atmospheric to a predetermined vacuum vacuum. After the pressure in the vessel becomes lower than the saturated vapor pressure, the liquid begins to boil. By neglecting the heat exchange of the bath with the environment, it can be assumed that the cooling rate is proportional to the rate of evaporation, which, in turn, is determined by the rate of steam pumping.

If the process requires stabilization of moisture in the dairy product, the cooling from the pasteurization temperature to the initial milk temperature is carried out only by pumping out steam without heat exchange of the container with the environment. After that, further cooling is carried out with ice water, which is fed into the jacket of the tank. . . . .

If it is necessary to reduce the moisture in the milk product during the cooling process due to boiling liquid and pumping out steam, a coolant is supplied to the jacket of the tank. Then the cooling process is thereby slowed down or even stopped while the moisture is being evaporated and pumped out. Thus, with the additional evaporation of moisture, for example, with a decrease in the moisture content by 1% of the initial mass of 1500 kg, the additional amount of heat supplied during the conduction heating is Q rm. 2450 15 36.8 MJ. Additional heating is carried out by supplying an appropriate amount of steam from the steam boiler to the jacket of the tank. Monitoring and measuring the amount of heat supplied or removed is advisable to carry out by changing the temperature of the dairy product while discontinuing the evacuation (steam pumping). For example, after cooling a dairy product, only due to vacuuming, to the initial temperature of 20 ° C, the evacuation of steam is stopped and the product is heated by

supplying steam to the jacket of the tank. So, the heating temperature

36.8 103 kD

well

1500 kg

.

cm 4.2 kJ / kg. hail

5.8 ° C -; - .-. -

After that, continue cooling, for example, to 20 ° C only due to vacuum pumping of steam. The cooling of the product to a temperature below the initial one is carried out in a known manner by cold or ice water, while the moisture content does not change.

To increase the moisture in the dairy product, coolant is supplied to the jacket of the tank, thereby increasing the cooling rate and leaving an excessive amount of moisture in the dairy product. Thus, with an increase in moisture content of 1%, or 15 kg for 1500 kg of milk, cold or ice water for heat removal of 36.8 MJ is fed into the jacket of the tank, in the back of the previous case.

In order to increase the capacity of rio steam and vacuum in the tank, the refrigerant is first fed to the inlet by the water ring pump, the temperature in its working cavity is lowered, and then into the jacket of the tank.

Example. Heating 1500 kg of milk in a typical capacity of 2 m.

Accept temperature gradient milo5

ten

15

20

25

The dairy product can be cooled from a temperature of 75 to 35 ° C and can be carried out for 30 minutes using a liquid ring vacuum pump of adequate capacity. By increasing the pumping speed, the heat transfer is proportionally increased and the cooling time of the dairy product is shortened .-, The use of the proposed pasteurization of dairy products allows to achieve higher productivity, quality and sterility of production.

Claims (2)

1. Method of pasteurization of dairy products in a tank, including heating with simultaneous stirring to pasteurization temperature, aging and conducting cooling to a predetermined temperature, characterized in that, in order to reduce the processing time and improve the quality of the product, heating is carried out by periodically bubbling saturated water vapor in the bottom layer, and after aging, the container is sealed followed by vacuum to the initial temperature of the dairy product, and the diameter of the vapor bubbles is are derived from the relationship. d 1,82g ftS Yao G (r + c © G  ka 0 - 5 C, pipe diameter 30 mm, d 5 and 10 mm. From the heat balance, the amount of steam supplied to heat 1500 kg of milk from 20 to 75 ° C is about 120 kg. From the proposed ratio for a diameter of 5 mm G / n 11.kg / m; for a bubble diameter of 10 mm, respectively 10kg / m. which determines, at a frequency of movements of 10, the steam supply rate, respectively, 220 and 190 kg / h and provides heating of the dairy product in about 30 and 40 minutes. Increasing the frequency of movement in proportion to the increase in the permissible steam supply rate. From the above numerical examples, it can be seen that the upper limit of the speed of steam substitution is about 1000 kg / h and the minimum pasteurization time of milk is about 10 minutes. where ft is the volume expansion of milk, degree 1; V, I - respectively kinematic 9 viscosity, m / s and thermal conductivity. W / m red; h.- .. g, s — heat of condensation, J / kg and heat capacity of steam, J / kg-g; 0- average temperature gradient in milk, hail ;. G - steam supply per unit of the horizontal surface of the tank, kg / m-s; n is the frequency of mixing,. 2. The method according to claim 1, wherein the fact that, in order to control the moisture content of the dairy product, in the process of evacuating a conductive heating or additional cooling. (J (J CT N . - r.i: ls - i-2 &: 3 f iЈi $$ l - Ji rk f: f:;.  -;: fe:,.:,.; -. , - :: - "/ -.:. srag.1 ..;: four, vv / Editor N. Lazarenko Compiled by A. Berlin Tehred M.MorgentalKorrektor N. Revska 0 o -t, o o-t ,;, D 7 FA / G.2